US10062600B2 - System and method for bi-facial processing of substrates - Google Patents

Abstract

A system for processing substrates in plasma chambers, such that all substrates transport and loading/unloading operations are performed in atmospheric environment, but processing is performed in vacuum environment. The substrates are transported throughout the system on carriers. The system's chambers are arranged linearly, such that carriers move from one chamber directly to the next. A conveyor, placed above or below the system's chambers, returns the carriers to the system's entry area after processing is completed. The carriers are configured for supporting substrates of different sizes. The carriers are also configured for flipping the substrates such that both surfaces of the substrates may be processed.

Description

RELATED APPLICATIONS

This application claims priority benefit from U.S. Provisional Application Ser. No. 61/942,594, filed on Feb. 20, 2014, and U.S. Provisional Application Ser. No. 61/943,999, filed on Feb. 24, 2014, and is a continuation-in-part of U.S. patent application Ser. No. 13/871,871, filed on Apr. 26, 2013, and which claims priority benefit from U.S. Provisional Application Ser. No. 61/639,052, filed on Apr. 26, 2012, the entire disclosures of which are incorporated herein by reference.

BACKGROUND

1. Field

This invention relates to bi-facial processing of substrates, such as substrates used for solar cells, for flat panel displays, etc.

2. Related Art

Various systems are known in the art for fabricating semiconductor IC's, solar cells, touch screens, etc. The processes of these systems are conducted in vacuum and include, e.g., physical vapor deposition (PVD), chemical vapor deposition (CVD), ion implant, etch, etc. There are two basic approaches for such systems: single-substrate processing or batch processing. In single wafer processing, only a single substrate is present inside the chamber during processing. In batch processing several substrates are present inside the chamber during processing. Single substrate processing enables high level of control of the process inside the chamber and the resulting film or structure fabricated on the substrate, but results in a relatively low throughput. Conversely, batch processing results in less control over the processing conditions and the resulting film or structure, but provides a much higher throughput.

Batch processing, such as that employed in systems for fabricating solar cells, touch panels, etc., is generally performed by transporting and fabricating the substrates in a two-dimensional array of n×m substrates. For example, a PECVD system for solar fabrication developed by Roth & Rau utilizes trays of 5×5 wafers for a reported 1200 wafers/hour throughput in 2005. However, other systems utilize trays having two dimensional arrays of 6×6, 7×7, 8×8, and even higher number of wafers, such that a larger number of substrates are processed simultaneously. While throughput is increased utilizing trays of two-dimensional wafer arrays, the handling and the loading and unloading operations of such large trays becomes complex.

In some processes, it is required to apply bias, e.g., RF or DC potential, to the substrate being processed. However, since batch system utilize a moving tray with the substrates, it is difficult to apply the bias.

Also, while some processes can be performed with the substrate held horizontally, some processes can benefit from a vertically held substrate. However, loading and unloading of substrate vertically is complex compared to horizontal loading and unloading.

Some processes may require the use of masks to block parts of the substrate from the particular fabrication process. For example, masks may be used for formation of contacts or for edge exclusion to prevent shunting of the cell. That is, for cells having contacts on the front and back sides, materials used for making the contacts may be deposited on the edges of the wafer and shunt the front and back contacts. Therefore, it is advisable to use mask to exclude the edges of the cell during fabrication of at least the front or back contacts.

As another illustration, for the fabrication of silicon solar cells, it is desirable to deposit blanket metals on the back surface to act as light reflectors and electrical conductors. The metal is typically aluminum, but the blanket metals could be any metal used for multiple reasons, such as cost, conductivity, solderability, etc. The deposited film thickness may be very thin, e.g., about 10 nm up to very thick, e.g., 2-3 um. However, it is necessary to prevent the blanket metal from wrapping around the edge of the silicon wafer, as this will create a resistive connection between the front and back surfaces of the solar cell, i.e., shunting. To prevent this connection, an exclusion zone on the backside edge of the wafer can be created. The typical dimension of the exclusion zone is less than 2 mm wide, but it is preferable to make the exclusion as thin as possible.

One way to create this exclusion zone is through the use of a mask; however, using masks has many challenges. Due to the highly competitive nature of the solar industry, the mask must be very cheap to manufacture. Also, due to the high throughputs of solar fabrication equipment (typically 1500-2500 cells per hour), the mask must be quick and easy to use in high volume manufacturing. Also, since the mask is used to prevent film deposition on certain parts of the wafer, it must be able to absorb and accommodate deposition build up. Furthermore, since film deposition is done at elevated temperatures, the mask must be able to function properly at elevated temperature, e.g., up to 350° C., while still accurately maintaining the exclusion zone width, while accommodating substrate warpage due to thermal stresses.

As another example, in many process flows it is desirable to flip the substrates so as to deposit films on both sides of the substrate. One example is bi-facial or other solar cells, where various layers of different materials are deposited on both the front and back surfaces of the substrate. However, using a large tray of two-directional substrate array makes the flipping operation complicated, or limited to manual operation wherein the tray is removed from the system and workers flip the substrates one by one, potentially leading the contamination and/or breakage. When referring to solar cells, the term “front surface” means the surface that would receive the direct solar radiation during service. When referring to touch screens, the term “from surface” refers to the surface the user's fingers will be touching.

For many thin film applications, the substrate size varies from product to product. This is especially true for touch panel displays. There are many different size pad computers and smartphones, and it would be advantageous to be able to use the same processing system to process all of these substrates. However, changing the substrates during processing is labor intensive manual process which does not lend itself to high volume manufacturing.

Some systems utilize a simple tray, where the substrates sit in pockets. However, with such trays vertical processing is not possible. Also, loading and unloading substrates in such system is difficult to automate. Also, trays do not work well when the processing requires touching only the circumferential edges and not the surfaces of the substrates. It is also very important to prevent the substrate from contacting debris or particles from earlier deposition on larger substrates.

In view of the above, a universal carrier that retains the substrate by only touching the edges and can carry substrates in a vertical orientation is desired.

SUMMARY

The following summary is included in order to provide a basic understanding of some aspects and features of the invention. This summary is not an extensive overview of the invention and as such it is not intended to particularly identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented below.

Embodiments of the invention provide a system architecture that is modular, in that it enables using different processes and process steps, and versatile, in that it is suitable for fabrication of various devices, including, e.g., solar cells, flat panel displays, touch screens, etc. Moreover, the system can handle different types and sizes of substrates without reconfiguration, but by simply changing the susceptors used.

The system architecture enables substrate handling, such as loading and unloading in atmospheric environment, separate from the vacuum processing. Additionally, various embodiments enable manual loading and unloading with automation in idle or not present, i.e., the system can be implemented without loading/unloading automation. Inside the vacuum environment the system enables static or pass-by processing of the substrates. In certain embodiments, vacuum isolation is provided between each processing chamber, using actuated valves. Various embodiments provide for electrostatic chucking of the substrates to enable efficient cooling and to prevent accidental movement of the substrates. In other embodiments, mechanical chucking is enabled using, e.g., spring-loaded clips with relief mechanism for loading/unloading of the substrates. Various embodiments also enable biasing of the substrates using, e.g., RF or DC bias power, or floating the substrate.

Various embodiments enable simplified handling of substrates by having the handling performed on line-array (i.e., 1×n) carriers, while processing is performed on a two-dimensional array of n×m substrates, by processing several (i.e., m) line-array carriers simultaneously. Other embodiments provide for transport mechanism wherein the substrates are processed in a vertical orientation, but loading and unloading is performed while the substrates are handled horizontally.

Embodiments of the invention also enable substrate processing using masks, which can be implemented by using a dual-mask arrangement. The two part masking system is configured for masking substrates, and includes an inner mask consisting of a flat metal sheet having apertures exposing the parts of the wafer that are to be processed; and, an outer mask configured for placing over and masking the inner mask, the outer mask having an opening cut of size and shape similar to the size and shape of the substrate, the outer mask having thickness larger than thickness of the inner mask. A mask frame may be configured to support the inner and outer masks, such that the outer mask is sandwiched between the mask frame and the inner mask. In one example, where the dual-mask arrangement is used for edge isolation, the opening cut in the inner mask is of size slightly smaller than the solar wafer, so that when the inner mask is placed on the wafer it covers peripheral edge of the wafer, and the opening cut in the outer mask is slightly larger than the opening cut in of the inner mask. A top frame carrier may be used to hold the inner and outer mask and affix the inner and outer masks to the wafer susceptor.

In certain embodiments, the line-array (i.e., 1×n) carriers are configured to be rotatable (flipped upside-down) so as to expose either side of the substrate to processing. The line-array (i.e., 1×n) carriers can be designed symmetrically about a rotation axis, so that one surface of the line-array substrate is processed, then the carriers rotate and the opposite surface of the substrates is processed. The substrates may be held by clips at their periphery, such that the front and back surfaces are not obscured for processing.

A loading and unloading mechanism is provided, which handles several, e.g., four rows of substrates simultaneously. The loading/unloading mechanism is configured for vertical motion, having a lowered position and an elevated position. In its lowered position, the mechanism is configured to simultaneously: remove a row of processed substrates from one carrier, deposit a row of fresh substrates on an empty carrier, deposit a row of processed substrates on a substrate removal mechanism, and collect a row of fresh substrates from a substrates delivery mechanism. The substrate removal mechanism and the substrate delivery mechanism may be conveyor belts moving in the same or opposite directions. In its elevated position, the mechanism is configured to rotate 180 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, exemplify the embodiments of the present invention and, together with the description, serve to explain and illustrate principles of the invention. The drawings are intended to illustrate major features of the exemplary embodiments in a diagrammatic manner. The drawings are not intended to depict every feature of actual embodiments nor relative dimensions of the depicted elements, and are not drawn to scale.

FIG. 1 illustrates an embodiment of a multi-substrate processing system, wherein transport carriers support a line-array of substrates, but processing is performed on a two-dimensional array of substrates.

FIG. 1A illustrates an example of a system wherein the carriers remain in a horizontal orientation during transport and processing, whileFIG. 1B illustrates an example wherein the carriers are horizontal during transport and loading/unloading, but are vertical during processing.

FIG. 2 illustrates a multi-wafer carrier according to one embodiment, whileFIG. 2A illustrates a partial cross-section.

FIG. 2B illustrates an example of carrier for processing silicon wafers, whileFIG. 2C illustrates an example of a carrier for processing glass substrates.

FIG. 3A is a top view, whileFIG. 3B is a side view of a load/unload mechanism according to one embodiment.FIG. 3C illustrates an embodiment for substrate alignment mechanism.

FIG. 4 illustrates an embodiment of avacuum processing chamber400 that may be used with the disclosed system.

FIG. 5 illustrates an embodiment for a mask and carrier assembly.

FIGS. 6A-6C illustrate three embodiments demonstrating how the vacuum chamber can be fitted with different processing sources of varying sizes and configurations.

FIGS. 7A-7E illustrate views of a multi-wafer carrier having an arrangement for dual-mask, according to various embodiments.

FIG. 8 is a cross section of an enlarged part of the frame, outer and inner masks, according to one embodiment, andFIG. 8A is a cross section of an enlarged part of the frame, outer and inner masks, according to anther embodiment.

FIG. 9 illustrates an embodiment of the outer mask, with the inner mask nested therein.

FIG. 10 illustrates an embodiment of the inner mask for use in edge isolation.

FIG. 11 illustrate an embodiment of the single wafer carrier.

FIG. 12 illustrate an embodiment of the outer mask, viewing from the underside.

FIG. 13 illustrates an embodiment of a top frame to support the inner and outer masks.

FIG. 14 illustrates an embodiment of the inner mask for creating plurality of holes in the wafer.

FIG. 15 illustrates an embodiment of the susceptor for use with the mask ofFIG. 9.

FIG. 16 illustrates an embodiment of a carrier elevator that may be used with various embodiments of the system disclosed herein.

FIG. 17 illustrates an embodiment of a carrier that may be used with different size and different types of substrates in the same processing system.

FIG. 18 illustrates an embodiment of a dual-sided flip carrier that may be used with different size and different types of substrates in the same processing system.

FIGS. 19A and 19B illustrate an embodiment of a simple substrate clip that can be used in a dual-sided flip carrier for different size and different types of substrates.

FIGS. 20A and 20B illustrate an embodiment of a loading and unloading module that can be used with various systems as disclosed herein.

FIG. 21 illustrates an embodiment of automation arrangement for loading and unloading substrates from carriers.

FIG. 22 illustrates an embodiment of substrate carrier arrangement that can be processed in a horizontal or vertical orientation, whileFIG. 23 illustrates the arrangement ofFIG. 22 in a vertical placement.

FIG. 24 illustrates an embodiment of substrate carrier arrangement that can be flipped so as to process both surfaces of the substrates.

FIG. 25 illustrates an embodiment of a system wherein the substrate carrier arrangement can be flipped so as to process both surfaces of the substrates.

DETAILED DESCRIPTION

The following detailed description provides examples that highlight certain features and aspects of the innovative processing system claimed herein. Various disclosed embodiments provide for a system wherein multiple substrates, e.g., semiconductor or glass substrates, are processed simultaneously inside a vacuum processing chamber, such as, e.g., a plasma processing chamber. While glass substrates, such as those used for touchscreens are not generally considered wafers, it should be appreciated that references made to wafers in this disclosure are made for convenience and ease of understanding, but that glass substrates may be substituted for all such references.

FIG. 1 is a top-view illustration of an embodiment of a multi-substrate processing system, wherein transport carriers support a line-array of substrates, but processing is performed on a two-dimensional array of substrates. In thesystem100 illustrated inFIG. 1, the substrates are loaded and unloaded at load/unloadstation105, i.e., from the same side of the system. However, it should be appreciated that the system may also be designed such that a loading station is provided on one side of the system, while an unloading station is provided on the opposite side of the system. In some embodiments, loading and/or unloading of substrates onto/from the carriers may be performed manually, while in others automation is provided to perform one or both of these tasks.

The substrates are loaded onto carriers positioned in load/unloadstation105, and which were transported fromcarrier return station110. Each carrier supports a linear array of substrates, i.e., two or more substrates arranged in a single row, in a direction perpendicular to the direction of travel inside the system. From load/unloadstation105 the carriers are moved via thecarrier return station110 tobuffer station115. The carriers are parked inbuffer station115 until the low vacuum loadlock (LVLL)120 is ready to accept them. In some embodiments, which will be described later, the buffer station also serves as the tilting station, wherein horizontally oriented carriers are tilted 90° to assume a vertical orientation. In such embodiments, clips are used to hold the substrate in place when assuming a vertical orientation.

At the proper time,valve112 opens and the carriers positioned inbuffer station115 are transported intoLVLL120.Valve112 is then closed and theLVLL120 is evacuated to a rough vacuum level. Thereaftervalve113 opens and the carriers fromLVLL120 are transported into high vacuum loadlock (HVLL)125. Once HVLL has been pumped to its vacuum level,valve114 opens and the carriers fromHVLL125 are transported intoprocessing chamber130. The system may have any number ofprocessing chambers130 aligned linearly such that the carriers may be transported from one chamber to the next via a valve positioned between each two processing chambers. At the end of the last processing chamber, a valve is positioned that leads to the reverse loadlock arrangement as in the entrance to the system, i.e., first a HVLL and then a LVLL. Thereafter the carriers exit to thecarrier return module135 viavalve116. Fromreturn module135 the carriers are returned tocarrier return station110 using, e.g., conveyor positioned above or below the processing chambers130 (not shown).

In general, the designer of vacuum processing systems faces two competing solutions: for easy loading/unloading and automation, it is better to have the substrate carriers designed to carry a small number of substrates, with the ultimate having each carrier supporting a single substrate. Conversely, for throughput and efficiency in vacuum pumping, it is preferable that the carriers carry the maximum possible number of substrates—which leads to difficulties in loading/unloading and automation. A feature disclosed herein is a system wherein each carrier supports a given number of substrates, e.g., and array of N×M substrates, but each step within the vacuum system is carried out on multiple carriers simultaneously. For example, if k carriers are operated upon simultaneously, then in each processing step the system operates on k×N×M substrates.

To provide a numerical example, it is much simpler to design loading/unloading automation for a carrier that supports six substrates than one that supports eighteen substrates. So, in one example, a carrier is designed to support an array of 2×3 substrates. However, each step in the system, including the loadlock, is designed to be carried out on three carriers simultaneously. Thus, for example, the loadlock is vacuum pumped after three carriers have entered the loadlock. Thus, after pumping the loadlock, 18 substrates are in vacuum inside the loadlock. Further, a simpler design can be pursued wherein each carrier supports a linear array, i.e., 1×M of substrates. For the same effect, one may use three carriers having 1×6 substrates each, of six carriers having 1×3 substrates each. In summary, each carriers is configured to carry a given number of substrates, and each vacuum chamber is configured to accommodate and operate simultaneously on a plurality of carriers.

For simplicity, the following examples are described with respect to a system wherein each carrier supports a linear array of substrates, which makes it easier to load and unload the substrates, and makes the carriers much easier to manufacture, handle, and transport. However, in order to have high throughput of the system, eachprocessing chamber130 is configured to house and simultaneously process a two-dimensional array of substrates positioned on several, i.e., two or more, carriers positioned one after the other. For better efficiency, in the particular embodiment ofFIG. 1,buffer station115,LVLL120 andHVLL125 are each configured to simultaneously house the same number of carrier as are simultaneously housed inside theprocessing chamber130. For example, each carrier may support three glass substrates in one row, but each processing chamber is configured to process two carriers simultaneously, thus processing a two-dimensional array of 3×2 substrates.

According to other embodiments, the load locks and buffer chambers are sized to handle multiple carriers, e.g., two carriers, to provide for increased pump/vent, and pressure stabilization times. Also, a buffer chamber can be used to transition carrier motion from one of station to station motion to one of continues pass-by motion inside a processing chamber. For example, if one process chamber process carriers in stationary mode while the next chamber processes in pass-by mode, a buffer chamber may be placed between these two chambers. The carriers in the system create a continuous stream of carriers in the process chamber or module, and each process chamber/module may have 5-10 carriers continuously moving in a head to toe fashion past the process source (e.g., heat source, PVD, etch, etc).

As shown inFIG. 1, the parts of the system dedicated for transport, loading and unloading of substrates are positioned in atmospheric environment. On the other hand, all processing is performed in vacuum environment. Transport, loading and unloading in atmospheric environment is much easier than in vacuum.

FIG. 1A illustrates an example of a system, such as that shown inFIG. 1, wherein thecarriers200 remain in a horizontal orientation during transport and processing. The carriers are returned to the starting point viaconveyor140 positioned above the processing chambers. As shown inFIG. 1A, eachcarrier200 supports foursubstrates220 arranged linearly in one row. Also, for explanation purposes, the top part ofchamber120 is removed, so as to expose the arrangement of six carriers positioned simultaneously therein. Therefore, according to this embodiment, while each carrier supports four substrates, each chamber process twenty-four substrates simultaneously.

FIG. 1B illustrates an example wherein the carriers are horizontal during transport and loading/unloading, but are vertical during processing. The arrangement ofFIG. 1B is very similar to that ofFIG. 1A, except that the loadlock and processing chambers are flipped vertically, so as to process the substrates in a vertical orientation. The construction of loadlock and processing chambers in both embodiments ofFIGS. 1A and 1B may be identical, except that inFIG. 1A they are mounted horizontally, while inFIG. 1B they are mounted on their side vertically. Consequently, thebuffer stations115 and thebuffer station145 on the other end of the system, are modified to include a lifting arrangement which changes the orientation of the carriers 90°, as shown inbuffer station145.

FIG. 2 illustrates a line-array carrier according to one embodiment, which may be configured for processing silicon wafers, glass substrates, etc. As shown inFIG. 2, the construction of the line-array carrier according to this embodiment is rather simple and inexpensive. It should be appreciated that the carrier can be configured for a different number of substrates and substrate size, by simply mounting different chucks on top of the carrier. Also, it should be appreciated that each processing chamber may be configured to accommodate several carriers simultaneously, thus processing multiple wafers on multiple carriers simultaneously.

Thecarrier200 ofFIG. 2 is constructed of asimple frame205 which is formed by twotransport rails225 and twoceramic bars210. Theceramic bar210 improves thermal isolation of the susceptor (not shown) attached thereto from the remaining parts of the chamber. At least one side of eachceramic bar210 forms afork arrangement235 with thetransport rail225, as shown in the callout. Acavity245 is formed in thefork arrangement235, such that theceramic bar210 is allowed to freely move (illustrated by the double-head arrow) due to thermal expansion, and not impart pressure on thetransport rail225.

Amagnetic drive bar240 is provided on each of the transport rails225 to enable transporting the carrier throughout the system. The magnetic drive bars ride on magnetized wheels to transport the carrier. To enhance cleanliness of the system, the drive bars240 may be nickel plated. This magnetic arrangement enables accurate transport without sliding of the carrier due to high accelerations. Also, this magnetic arrangement enables large spacing of the wheels, such that the carrier is attached to the wheels by magnetic forces and may cantilever to a large extent to traverse large gaps. Additionally, this magnetic arrangement enables transport of the carrier in either vertical or horizontal orientation, since the carrier is attached to the wheels by magnetic forces.

Carrier contact assembly250 is attached to thetransport rail225 and mates with a chamber contact assembly252 (see callout) attached to the chamber. The chamber contact assembly has an insulatingbar260 having acontact brush262 embedded therein. Thecontact assembly250 has a conductive extension251 (FIG. 2A) that is inserted between an insulatingspring264 andinsulting bar260, thus being pressed againstbrush contact264 so as to receive bias potential from the mating contact. The bias may be used for, e.g., substrate bias, substrate chucking (for electrostatic chuck), etc. The bias may be RF or DC (continuous or pulsed). Thecarrier contact assembly250 may be provided on one or both sides of the carrier.

FIG. 2A is a partial cross-section showing how the carrier is transported and how it receives bias power. Specifically,FIG. 2A illustrates thedrive bar240 riding on threemagnetized wheels267, which are attached toshaft268.Shaft268 extends beyond thechamber wall269, such that it is rotated from outside the interior vacuum environment of the chamber. Theshaft268 is coupled to a motor via flexible belt such as, e.g., an O-ring, to accommodate variations in shaft diameter.

FIG. 2B illustrates an example of carrier for processing silicon wafers, e.g., for fabricating solar cells. InFIG.2B wafers220 may be chucked tosusceptor223 using, e.g., chucking potential. Alifter215 may be used to lift and lower the wafers for loading and unloading.FIG. 2C illustrates an embodiment wherein the carrier may be used for processing glass substrates such as, e.g., touchscreens. In this embodiment the substrates may be held in place using mechanical spring-loaded clamps or clips227. Thesusceptor224 may be a simple pallet with arrangement for the spring-loaded clips.

FIGS. 3A and 3B illustrate an embodiment for substrate loading and unloading mechanism, in conjunction with the carrier return.FIG. 3A is a top view of the load/unload mechanism, whileFIG. 3B is a side view. As shown inFIG. 1A, a conveyor returns the carriers after completion of processing. The carriers are then lowered byelevator107 and transported horizontally to the loading/unloading station105. As shown inFIGS. 3A and 3B, a dual conveyor, i.e.,conveyors301 and303, are used to bring fresh substrates for processing and remove processed wafers. It is rather immaterial which one brings the fresh wafers and which one removes the processed wafers, as the system would work exactly the same regardless. Also, in this embodiment it is shown thatconveyors301 and303 transport substrates in the opposite direction, but the same result can be achieved when both conveyors travel in the same direction.

The arrangement ofFIGS. 3A and 3B supports handling two carriers simultaneously. Specifically, in this embodiment processed substrates are unloaded from one carrier, while fresh substrates are loaded onto another carrier, simultaneously. Moreover, at the same time, processed substrates are deposited on the processed substrate conveyor and fresh substrates are picked-up from the fresh substrates conveyor, to be delivered to a carrier in the next round. This operation is performed as follows.

The substrate pick-up mechanism is configured to have two motions: rotational and vertical motions. Four rows ofchucks307 are attached to the substrate pick-upmechanism305. Thechucks307 may be, for example, vacuum chucks, electrostatic chucks, etc. In this specific example, four rows of Bernoulli chucks are used, i.e., chucks that can hold a substrate using Bernoulli suction. The four rows of chucks are positioned two rows on each side, such that when two rows of chucks are aligned with the carriers, the other two rows are aligned with the conveyors. Thus, when the pick-upmechanism305 is in its lowered position, one row of chucks picks up processed substrates from a carrier and another row deposits fresh substrates on another carrier, while on the other side one row of chucks deposit processed substrates on one conveyor and another row of chucks pick-up fresh substrate from the other conveyor. The pick-upmechanism305 then assumes its elevated position and rotates 180 degrees, wherein at the same time the carriers move one pitch, i.e., the carrier with the fresh substrates move one step, the carrier from which processed substrates were removed moves into a fresh substrate loading position, and another carrier with processed substrates moves into the unloading position. The pick-upmechanism305 then assumes its lowered position and the process is repeated.

To provide a concrete example, in the snapshot ofFIG. 3A,carrier311 has processed substrates which are being picked-up by one row of chucks on pick-uparrangement305.Carrier313 is being loaded with fresh substrates from another row of chucks of pick-uparrangement305. On the other side of pick-uparrangement305 one row of chucks is depositing processed substrates onconveyor303, while another row of chucks is picking up fresh substrates fromconveyor301. When these actions have been completed, pick-uparrangement305 is raised to its elevated position and is rotated 180 degrees, as shown by the curved arrow. At the same time, all of the carriers move one step, i.e.,carrier316 moves to the position previously occupied bycarrier317,carrier313, now loaded with fresh substrates, moves to the spot previously occupied bycarrier316,carrier311, now empty, moves to the spot previously occupied bycarrier313, andcarrier318, loaded with processed substrates moves into the spot previously occupied withcarrier311. Now the pick-up arrangement is lowered, such thatcarrier311 is loaded with fresh substrates, processed substrates are removed fromcarrier318, the substrates removed fromcarrier311 are deposited ontoconveyor303, and fresh substrates are picked-up fromconveyor301. The pick-uparrangement305 is then elevated, and the process repeats.

The embodiment ofFIGS. 3A and 3B also utilizes an optionalmask lifter arrangement321. In this embodiment, masks are used to generate a required pattern on the surface of the substrate, i.e., expose certain areas of the substrate for processing, while covering other areas to prevent processing. The carrier travels through the system with the mask placed on top of the substrate until it reaches themask lifer321. When a carrier with processed substrates reaches the mask lifter (inFIGS. 3A and 3B, carrier318), themask lifter321 assumes its elevated position and lifts the mask from the carrier. The carrier can then proceed to the unload station to unload its processed substrates. At the same time, a carrier with fresh substrates (inFIG. 3B carrier319), movers into the mask lifter arrangement andmask lifter321 assumes its lowered position so as to place the mask onto the fresh substrates for processing.

As can be appreciated, in the embodiment ofFIGS. 3A and 3B, the mask lifter removes the masks from one carrier and places them on a different carrier. That is, the mask is not returned to the carrier from which it was removed, but is rather placed on a different carrier. Depending on the design and number of carriers in the system, it is possible that after several rounds a mask would be returned to the same carrier, but only after being lifted from another carrier. The converse is also true, i.e., depending on the design and the number of carriers and masks in service, it is possible that each mask would be used by all carriers in the system. That is, each carrier in the system would be used with each of the masks in the system, wherein at each cycle of processing through the system the carrier would use a different mask.

As shown in the callout, the carrier elevator may be implemented by having two vertical conveyor arrangements, one on each side of the carriers. Each conveyor arrangement is made of one ormore conveyor belt333, which is motivated byrollers336. Lift pins331 are attached to thebelt333, such that as thebelt333 moves, thepins331 engage the carrier and move the carrier in the vertical direction (i.e., up or down, depending on which side of the system the elevator is positioned at and whether the carrier return conveyor is positioned over or below the processing chambers).

FIG. 3C illustrates an embodiment for substrate alignment mechanism. According to this embodiment,chuck345 has spring loaded alignment pins329 on one side and anotch312 on the opposite side. A rotating push-pin341 is configured to enter thenotch312 to push thesubstrate320 against thealignment pin329 and then retract, as illustrated by the dotted-line and rotational arrow. Notably, the rotating push-pin341 is not part of thechuck345 or the carrier and does not travel within the system, but is stationary. Also, the spring-loaded alignment pin is compressed to a lower position if a mask is used. Thus, a substrate alignment mechanism is provided which comprises a chuck having a first side configured with an alignment pin, a second side orthogonal to the first side and configured with two alignment pins, a third side opposite the first side and configured with a first notch, and a fourth side opposite the second side and configured with a second notch; the alignment mechanism further comprising a first push-pin configured to enter the first notch to push the substrate against the first alignment pin, and a second push-pin configured to enter the second notch and push the substrate against the two alignment pins.

FIG. 4 illustrates an embodiment of avacuum processing chamber400 that may be used with the disclosed system. In the illustration ofFIG. 4, the lid of the chamber is removed to expose its internal construction. Thechamber400 may be installed in a horizontal or vertical orientation, without any modifications to its constituents or its construction. The chamber is constructed of a simple box frame withopenings422 for vacuum pumping. Anentry opening412 is cut in one sidewall, while anexit opening413 is cut in the opposite sidewall, to enable thecarrier424 to enter the chamber, traverse the entire chamber, and exit the chamber from the other side. Gate valves are provided at eachopening412 and413, although for clarity in the illustration ofFIG. 4 only gate valve414 is shown.

To enable efficient and accurate transport of thecarrier424 in a horizontal and vertical orientation,magnetic wheels402 are provided on the opposing sidewall of the chamber. The carrier has magnetic bars that ride on themagnetic wheels402. The shafts upon which thewheels402 are mounted extend outside the chamber into an atmospheric environment, wherein they are motivated bymotor401. Specifically,several motors401 are provided, each motivating several shafts using belts, e.g., O-rings. Also,idler wheels404 are provided to confine the carriers laterally.

A feature of the embodiment ofFIG. 4 is that the diameter of the magnetic wheels is smaller than the chamber's sidewall thickness. This enables placing magnetic wheels inside the inlet andoutlet openings412 and413, as shown bywheels406 and407. Placingwheels406 and407 inside the inlet andoutlet opening412 and413 enables smoother transfer of the carriers into and out of the chamber, as it minimizes the gap that the carriers have to traverse without support from wheels.

FIG. 5 illustrates an embodiment for a mask and carrier assembly. Progressing from left to right along the curved arrow, a single-substrate mask assembly501 is mounted onto amask carrier503, supporting several mask assemblies; and themask carrier503 is mounted onto asubstrate carrier505. In one embodiment, springs between the floatingmask assemblies501 keep them in place for engagement with guide pins507, provided on thesubstrate carriers505, such that each mask is aligned to its respective substrate. Each single-substrate mask assembly is constructed of an inner foil mask that is cheap and capable of many repeated uses. The foil mask is made of s flat sheet of magnetic material with perforations according to a desired design. An outer mask covers and protects the inner mask by taking the heat load, so that the foil mask does not distort. An aperture in the outer mask exposes the area of the inner mask having the perforations. A frame holds the inner and outer masks onto themask carrier503. Magnets embedded in thesubstrate carrier505 pull the inner foil mask into contact with substrate.

Each substrate support, e.g., mechanical or electrostatic chuck,517 supports a single substrate. The individual chucks517 can be changed to support different types and/or sizes of substrates, such that the same system can be used to process different sizes and types of substrates, using the same carrier but with interchangeable susceptors. In this embodiment thechuck517 has substrate alignment pins519 which are retractable, and provisions to align the substrate on top of the chuck. In this embodiment, the provisions to enable alignment consist of aslit512 accommodating a retractable pusher pin that pushes the substrate against alignment pins519 and then retracts out of theslit512. This allows for aligning the substrate and the mask to the substrate carrier, such that the mask is aligned to the substrate. The retractable pusher pin assembly is attached to the loading station and not to the carrier. This dramatically reduces the number of pusher pins required, i.e., the system only needs as many pusher pins as the number of substrates supported on one carrier. Additionally, it also simplifies the construction of the carrier, since no alignment mechanism needs to be incorporated into the carrier.

As can be understood, the system described thus far is inexpensive to manufacture and provide efficient vacuum processing of various substrates, such as, e.g., solar cells, touchscreens, etc. The system can be configured with double or single end loading and unloading, i.e., substrate loading and unloading from one side, or loading from one side and unloading from the opposite side. No substrate handling is performed in vacuum. The system is modular, in that as many vacuum processing chambers as needed may be installed between the input and output loadlocks. The vacuum chambers have a simple design with few parts in vacuum. The vacuum chambers may be installed in a horizontal or vertical orientation. For example, for solar cell processing the system may process the substrates in a horizontal orientation, while for touchscreens the substrates may be processed in a vertical orientation. Regardless, loading, unloading and transport in atmospheric environment is done with the substrates in a horizontal orientation. The processing sources, e.g., sputtering sources, may be installed above and/or below the substrates. The system is capable of pass-by or static processes, i.e., with the substrate stationary or moving during vacuum processing. The chambers may accommodate sputtering sources, heaters, implant beam sources, ion etch sources, etc.

For solar applications the vacuum chamber may include a low energy implanter (e.g., less than 30 kV). For specific solar cell design, such as PERC, IBC or SE, the mask arrangement may be used to perform masked implant. Also, texture etch may be performed with or without mask, using an ion etch source or laser assisted etch. For point contact cells, masks with many holes aligned to the contacts can be used. Also, thick metal layers can be formed by serially aligning several PVD chambers and forming layers one over the other serially.

For touch panel applications, the chambers may be used to deposit cold and/or hot ITO layers using PVD sources. The processing is performed with several, e.g., three touch panels arranged widthwise on each carrier, and several, e.g., two, carriers positioned inside each chamber simultaneously for higher throughput but simpler handling. The same system can handle touchscreens for pads or cellphone size glass without any internal reconfigurations. Simply, the appropriate carrier is configured and the entire system remains the same. Again, no substrate handling is performed in vacuum.

The handling and processing operations can be the same for all types and sizes of substrates. An empty carrier moves to load from carrier return elevator. If a mask is used, the mask is removed and stays at the elevator. Substrates are loaded onto the carrier in atmospheric environment. Meanwhile a loaded carrier moves into the elevator and the masks are placed on top of the fresh substrates. The carrier then moves into the load lock. Once a predefined number pf freshly loaded carriers are inside the loadlock, the gate valve is closed and vacuum is pumped inside the loadlock. In vacuum the carrier transport is via simple magnetic wheels positioned in chamber wall and energized from outside the chamber in atmospheric or vacuum environment. The chambers can have valves for isolation, and can have sources above or in a drawer for process below the substrates. The substrates can be removed at an unload end of the system, or left on carriers to return to the loading end, i.e., entry side of the system. Carriers return on simple conveyor belt from process end of the system to load end of the system. Simple pin conveyor lifts or lowers the carriers to or from load and unload stations.

FIGS. 6A-6C illustrate three embodiments demonstrating how the vacuum chamber can be fitted with different processing sources of varying sizes and configurations. In the examples ofFIGS. 6A-6C it is assumed that the substrates are arrange three-wide, but of course more or less substrates can be arranged on a carrier widthwise. Also, inFIGS. 6A-6C it is assumed that the processing chamber can accommodate several carriers, e.g., two or three, for simultaneous processing. The sources illustrated inFIGS. 6A-6C may be any processing sources, such as, e.g., PVD, etch, implant, etc.

FIG. 6A illustrates an embodiment wherein asingle source601 is provided onchamber600. This single source is used to process all of the substrates positioned inside thechamber600. Thesource601 may have length and/or width that covers all of the substrates simultaneously. For some sources, it may be too complicated or too expensive to fabricate a single source with such a large size. For example, ifsource601 is a sputtering source, the target must be made very large, which is expensive, complicated, and leads to under-utilization. Therefore, according to the embodiments ofFIGS. 6B and 6C several smaller sources are used. In the embodiment ofFIG. 6B each of thesources603A-603C is wide enough to cover only a single substrate, but it may cover more than one substrate lengthwise, i.e., in the direction of substrate travel. By staggering the sources such that each source covers only one of the substrate in each carrier, all of the substrates can be processed. Such an arrangement is particularly suitable for pass-by processing. Conversely, in the embodiment ofFIG. 6C each of the sources606A-606C is wide enough to cover all of the substrates in one carrier, i.e., in a direction perpendicular to the substrate travel direction, but is too narrow to cover all of the substrates positioned within the chamber. In fact, in some embodiments each of the sources606A-606C is even narrower than one substrate. Such an arrangement is equally suitable for pass-by or static processing.

The embodiments described above provide for a vacuum processing chamber having a vacuum housing sized for housing and processing several substrate carriers simultaneously. The housing is also configured for supporting several processing sources simultaneously. The processing sources may be, e.g., sputtering sources, which may be narrow sources having length sufficient to traverse all substrates held by a substrate carrier, but may be narrower than the width of a substrate positioned on the carrier. Several such sources may be positioned back-to-back over the entire or part of the length of the chamber in the travel direction of the carrier. The chamber has several shafts positioned on two opposing sides to transport the carriers inside the chamber. Each shaft is rotated by a flexible belt that is motivated by a motor. Each shaft has several magnetic wheels positioned thereupon in alternating pole order, i.e., while one wheel may have its outside circumference magnetized south and inside diameter magnetized north, the neighboring wheel would have its outer circumference magnetized north and inside diameter magnetized south. The chamber also has an entry sidewall having an inlet opening and an exit sidewall opposite the entry sidewall and having an outlet opening; wherein a magnetized wheel arrangement is positioned inside the entry sidewall and protruding into the inlet opening and having a magnetized wheel arrangement positioned inside the exit sidewall and protruding into the outlet opening, so as to drive the substrate carriers passing through the inlet and outlet openings.

The disclosed system is a linear system wherein the chambers are arranged linearly, one chamber coupled to the next, such that substrate carriers enter the system from one side, traverse all the chambers in a linear fashion, and exit the system on the opposite side. The carriers move from one chamber directly to the next via valve gates separating the chambers. Once a carrier exits the vacuum environment of the system, it enters an elevator and is moved vertically to a return conveyor, which transport the carrier horizontally back to the entry side of the system, wherein it enters another elevator and is moved vertically to be loaded with fresh substrates and enter the vacuum environment of the system again. While the carrier is transported in atmospheric environment it is held in a horizontal orientation. However, in one embodiment, when the carrier enters the vacuum environment it is rotated to a vertical orientation, such that the substrates are processed while held in a vertical orientation.

The system may have a loading and unloading station positioned at the entry side of the system. The loading and unloading system has a rotating structure upon which four rows of chucks are positioned, two rows on each side of the rotation axis. On each side of the rotation axis one row of chucks is configured for unloading processed substrates and one row of chucks is configured for loading fresh substrates. The rotating structure is configured for vertical motions, wherein when it assumes its lower position the structure picks-up substrates and when it assumes its elevated position the structure rotates 180 degrees. Also, when the structure is in its lowered position, on each side of the rotation axis one row of chucks picks-up substrates while the other row of chucks deposits, i.e., releases, its substrates. In one embodiment, two conveyors are provided across the entry to the system, wherein one conveyor delivers fresh substrates while the other conveyor removes processed substrates. The rotating structure is configures such that in its lower position one row of chucks is aligned with the conveyor delivering fresh substrates while the other row of chucks is aligned with the conveyor removing processed substrates. Simultaneously, on the other side of the rotation axis, one row of chucks is aligned with an empty carrier while the other row of chucks is aligned with a carrier holding processed substrates.

In some embodiments provisions are made to apply potential to the substrates. Specifically, each carrier includes a conductive strip that, when the carrier enters a processing chamber, is inserted into a sliding contact comprising an elongated contact brush and a conformal insulating spring that is configured to press the conductive strip against the elongated contact brush. An insulating strip, such as a Kapton strip, can be used to attach the conductive strip to the carrier.

When processing of the substrates requires the use of masks, the masks may be placed individually on top of each substrate, or one mask may be formed to cover all substrates of one carrier simultaneously. The mask may be held in place using, e.g., magnets. However, for accurate processing the mask must be made very thin, and consequently may deform due to thermal stresses during processing. Additionally, a thin mask may collect deposits rapidly and the deposits may interfere with the accurate placing and masking of the mask. Therefore, it would be advantageous to use the dual-mask arrangement according to the embodiments disclosed below.

FIGS. 7A-7E illustrate views of a multi-wafer carrier (linearly arranged in this example) having an arrangement for dual-mask, according to various embodiments.FIG. 7A illustrates a multi-wafer carrier with dual-masks arrangement, wherein the mask arrangement is in the lower position such that the inner mask is in intimate physical contact with the wafer;FIG. 7B illustrates a multi-wafer carrier with dual-masks arrangement, wherein the mask arrangement is in the elevated position thereby enabling replacement of the wafers;FIG. 7C illustrates a multi-wafer carrier with dual-masks arrangement, wherein wafer lifters are included for loading/unloading wafers (wafers are omitted from this illustration);FIG. 7D illustrates a partial cross-section of a multi-wafer carrier with dual-masks arrangement, wherein the mask arrangement and the wafer lifters are in the elevated position; andFIG. 7E illustrates a partial cross-section of a multi-wafer carrier with dual-masks arrangement, wherein the mask arrangement and the wafer lifter are in the lower position.

Referring toFIG. 7A, the multi-wafer carrier, also referred to ascarrier support700 has three separate single-wafer carriers orsusceptors705, which are supported by a susceptor frame or bars710, made of, e.g., ceramic. Each single-wafer carrier705 is configured for holding a single wafer together with a dual-mask arrangement. InFIG. 7A the dual-mask arrangement is in a lowered position, but no wafer is situated in any of the carriers, so as to expose the carriers' construction. InFIG. 7B the dual-mask arrangement is shown in the lifted position, again without wafers in any of the carriers. In the embodiments ofFIGS. 7A-7E alifter715 is used to lift and lower the dual-mask arrangement; however, for lower cost and less complication,lifter715 may be eliminated and the dual-mask arrangement may be lifted manually. Also, a mask lifting arrangement can be provided in the load/unload station. Transport rails725 are provided on each side of theframes710, to enable transporting thecarrier700 throughout the system.

Each of single-wafer carriers705 has a base730 (visible inFIG. 7B), which has a raisedframe732 with arecess735 to support a wafer suspended by its periphery. The base730 with theframe732 form apocket740 below the suspended wafer, which is beneficial for capturing broken wafer pieces. In some embodiments, theframe732 is separable from thebase730.Outer mask745 is configured to be mounted on theframe732, so as to cover theframe732 and cover the periphery of the inner mask, but expose the central part of the inner mask which corresponds to the wafer. This is exemplified by the cross-section illustration in the embodiment ofFIG. 8.

InFIG. 8, base orsusceptor805 has raisedframe832 with recess835, which supportswafer820 at its periphery. The base830 withframe832forms pocket840, and thewafer820 is suspended above the pocket. A series ofmagnets834 are positioned inside the raisedframe832, so as to surround the periphery of thewafer820. In some embodiments, especially for high temperature operations, themagnets834 may be made of Samarium Cobalt (SmCo)Inner mask850 is positioned on top of the raisedframe832 and thewafer820, and is held in place bymagnets834, such that it physically contacts the wafer.Outer mask845 is placed over and physically contacts theinner mask850, such that it covers the periphery of theinner mask850, except for the area of the inner masks that is designed for imparting the process to the wafer. An example ofouter mask945 is shown inFIG. 9, in this example made of a folded (e.g., stamped) sheet of aluminum, wherein the inner mask is covered by the outer mask, except for a smallperipheral edge952, since the example is for an edge shunt isolation processing. An example of theinner mask750 for edge shunt isolation is illustrated inFIG. 10, which is basically a flat sheet of metal having an aperture of size and shape as that of the wafer, except that it is slightly smaller, e.g., 1-2 mm smaller than the size of the wafer. In the embodiment ofFIG. 8,mask frame836 is provided to enable supporting and lifting of the inner and outer mask off of the carrier. In such a configuration, theouter mask845 is sandwiched between themask frame836 and theinner mask850.

FIG. 8A illustrates another embodiment, which may be used, for example, for forming contact patterns on the back of a wafer. In this embodiment, the susceptor forms a top platform to support the wafer on its entire nack surface.Magnets834 are embedded over the entire area of the suscpetor below the top surface of the susceptor. Theinner mask850 covers the entire surface of thewafer820 and has plurality of holes according to the contact design.

Turning back toFIGS. 7A-7E,lifter715 can be used to raise the outer mask, together with the inner mask. Also,wafer lifter752 can be used to lift the wafer off of theframe730, so that it could be replaced with a fresh wafer for processing, using a robot arm. However,lifters715 and752 can be eliminated and the operations of lifting the masks and replacing the wafer may be done manually, or by other means, instead.

In the embodiments described above with reference toFIG. 8, the carrier supports the wafer on its peripheral edge, such that the wafer is suspended. The pocket formed below the wafer traps broken wafer pieces and prevents wraparound of deposited material. On the other hand, in the embodiment ofFIG. 8A the wafer is supported over its entire surface. The mask assembly is lowered in place for sputter or other form of processing, and is lifted, manually or mechanically, for loading and unloading of wafers. A series of magnets on the carrier help secure the inner mask in place and in tight contact with the wafer. After repeated uses, the outer and inner masks can be replaced, while the rest of the carrier assembly can be reused. Theframe710, also referred to as mask assembly side bars, may be made from low thermal expansion material, such as Alumina or Titanium.

According to the above embodiments, the inner mask establishes an intimate gap free contact with the substrate. The outer mask protects the inner mask, the carrier and the carrier frame from deposited material. In the embodiments illustrated, the outer and inner mask openings are in a pseudo-square shape, suitable for applications to mono-crystalline solar cells during edge shunt isolation process. During other processes the inner mask has a certain apertures arrangement, while the outer mask has the pseudo-square shaped aperture. Pseudo-square shape is a square with its corners cut according to a circular ingot from which the wafer was cut. Of course, if poly-crystalline square wafers are used, the outer and inner mask openings would be square as well.

FIG. 11 illustrate an embodiment of thesingle wafer susceptor1105, corresponding to the embodiment ofFIG. 8. The wafer rests at its periphery onrecess1132.Magnets1134, shown in broken line, are provided inside the carrier all around the wafer. Alignment pins1160 are used to align the outer mask to thesusceptor1105. An embodiment of the outer mask is shown inFIG. 12, viewing from the underside. Theouter mask1245 is fabricated by stamped sheet metal. It has alignment holes orrecesses1262 corresponding to the alignment pins1260 of the carrier1205. Theouter mask1245 is configured to cover and protect the susceptor.

FIG. 13 illustrates an embodiment of atop frame1336 used to hold the outer and inner masks and secure the masks to the susceptor. Thetop frame1336 may be made by, e.g., twolongitudinal bars1362, held together by twotraverse bars1364. The outer mask is held insidepocket1366. Alignment holes1368 are provided to align the top frame to the susceptor.

FIG. 14 illustrates an example of an inner mask with a hole-pattern designed, for example, for fabricating plurality of contacts on the wafer. Such an inner mask can be used with the susceptor shown inFIG. 15, wherein themagnets1534 are distributed over the entire area below the surface of the wafer. The magnets are oriented in alternating polarization.

An upper or outer mask may be made from thin, e.g., about 0.03″, aluminum, steel or other similar material, and is configured to mate with a substrate carrier. An inner mask is made from a very thin, e.g., about 0.001 to 0.003″, flat steel sheet, or other magnetic materials, and is configured to be nested within the outer mask.

According to further embodiments, arrangement for supporting wafers during processing is provided, comprising: a wafer carrier or susceptor having a raised frame, the raised frame having a recess for supporting a wafer around periphery of the wafer and confining the wafer to predetermined position; an inner mask configured for placing on top of the raised frame, the inner mask having an aperture arrangement configured to mask part of the wafer and expose remaining part of the wafer; and an outer mask configured for placing over the raised frame on top of the inner mask, the outer mask having a single opening configured to partially cover the inner mask. A top frame carrier may be used to hold the inner and outer mask and affix the inner and outer masks to the wafer susceptor.

Magnets are located in the susceptor and alternate N-S-N-S-N completely around the frame or completely below the entire surface of the susceptor and directly under the wafer. The outer and inner masks are designed to be held to the frame by magnetic forces only, so as to enable easy and fast loading and unloading of substrates.

The mask assembly is removable from the wafer carrier and support frame to load the substrate into the carrier. Both the outer and inner masks are lifted as part of the mask assembly. Once the wafer is located on the carrier in the wafer pocket, the mask assembly is lowered back down onto the carrier. The inner mask overlaps the top surface of the wafer. The magnets in the carrier frame pull the inner mask down into intimate contact with the substrate. This forms a tight compliant seal on the edge of the wafer. The outer mask is designed in order to prevent deposition on the thin compliant inner mask and on the susceptor. As explained above, the deposition process might cause the inner mask to heat, causing the mask to warp and loose contact with the wafer. If the mask looses contact with the wafer the metal film will deposit in the exclusion zone on the surface of the substrate wafer. The pocket and friction force created by the magnets keep the substrate and mask from moving relative to each other during transport and deposition, and the outer mask prevents film deposition on the inner mask and prevents the inner mask from warping.

The mask assembly can be periodically removed from the system with the carrier by use of a vacuum carrier exchange. The carrier exchange is a portable vacuum enclosure with carrier transport mechanism. It allows the carriers to be exchanged “on the fly” without stopping the continuous operation of the system.

As disclosed above, in certain embodiments the carriers are returned in atmospheric environment, for example, on a conveyor above the vacuum processing chambers. In such embodiments, the carriers can be lifted and/or lowered using an elevator.FIG. 16 illustrates an embodiment of a carrier elevator that may be used with various embodiments of the system disclosed herein. Theelevator1600 is constructed rather simply and inexpensively, in part due to the simplified design of the carriers. In general, theelevator1600 is constructed by implementing a vertically moving conveyor belt or chain,1605, which haspins1607 extending orthogonally to the direction of travel therefrom. As theconveyor1605 moves, thepins1607 engage and lift thecarriers1610.

InFIG. 16,carrier1610 is shown without substrates or masks on load/unload orbuffer station1620. If used for loading,buffer station1620 has substrate alignment mechanism which, in this embodiment, includessubstrate alignment pins1612 which extend through openings in thecarrier1610. In this embodiment, once the substrates are aligned on top of the carrier, the substrates may be chucked and the alignment pins1612 may be lowered and the carrier travels without thepins1612. Also, if a masking scheme is used,mask alignment pins1614 extend through openings in the carrier and the masks so as to align the masks to each substrate individually. Once aligned, themask alignment pins1614 can be disengaged such that the carrier travels without the mask alignment pins1614.

This elevator arrangement can be implemented in systems that do or do not use masks over the substrates. As shown in the example ofFIG. 16, thecarrier1610 is moved into theconveyor station1600 and amask lifter1613 engages and lifts themask assembly1615 off of thecarrier1610. Thecarrier1610 is then moved to load/unloadstation1620 wherein processed substrates are removed and fresh substrates are loaded. InFIG. 16 thecarrier1610 is illustrated after processed substrates have been removed, but before fresh substrates have been loaded. Alignment pins1614 extend at the load/unload station to ensure proper alignment of the substrates on thecarrier1610. Then thepins1614 are lowered and the carrier is returned to theconveyor station1600. If no mask is used, theconveyor1605 is then moved up so that the pins of the conveyor engage and lift the carrier and deliver it to the next stage in the process sequence.

Conversely, when masks are used, after thecarrier1610 is delivered to theconveyor1600, themask lifter1613 then lowers themask assembly1615 to deposit themask assembly1615 back over thecarrier1610. InFIG. 16 the mask assembly includes amain frame1616 and threeindividual masks1619. The carrier is then returned to theload station1620 and themask alignment pins1614 are raised so as to align each mask to the corresponding individual substrate. Themask alignment pins1614 can then be lowered and thecarrier1610 can be moved to the next step in the process.

FIG. 17 illustrates an embodiment of a universal carrier that may be used with different sizes and different types of substrates in the same processing system, or a system having the same architecture as disclosed herein, except that the chamber sizes may be changed to accommodate different size substrates. This feature enables the reuse of as many common elements as possible, even when the chamber size needs to be changed. For example, the entire carrier transport system, including the elevator, can be identical, using the same parts for any size system. Use of the same parts reduces the overcall cost of the system due to economies of scale.

In the example ofFIG. 17, the universal carrier is illustrated in three different configurations:carrier1701 is configured to accept masks for fabrication of, e.g., solar cells;carrier1702 is a carrier without a mask and may be during, e.g., ion implantation or etching; andcarrier1703 is configured for supporting glass substrates for fabrication of, e.g., touch panels for cellphones or pads. All three carriers can be used with the same transport system, such that they may be used in the same processing system. For this objective, the carrier comprises acommon rail1705 that is the same for all carriers, e.g.,carriers1701,1702, and1703, and is designed to engage with the transport mechanism and the elevator, when used. A carrier body is designed specifically for each application, and it is attached to thecommon rail1705. Also, each carrier body has a specific substrate attachment mechanism that fits the particular substrate used for the application, e.g., silicon wafers for solar cells or glass for touch screens. For example,carrier body1707 hasbases1708 configured to accept substrate thereupon. Thebases1708 may be, e.g., a simple susceptor, an electrostatic chuck, etc. Conversely,body1706 hasclips1709 designed to engage the substrate, such as, e.g., glass panels.

FIG. 18 illustrates an embodiment of a dual-sided flipable carrier that may be used with different sizes and different types of substrates in the same processing system. As shown, the carrier may be formed usingcommon rails1805, similar to that in the embodiment ofFIG. 17. Thecarrier body1806 is made of simple slidingrails1802 that may be made of inexpensive sheet metal. In some embodiments the slidingrails1802 may be spring loaded to be normally in the closed position, i.e., the position engaging thesubstrates1801. To load substrates, the slidingrails1802 are slid to the open position, as illustrated by the double-lined arrows, thesubstrates1801 are positioned between theclips1808, and therails1802 are allowed to return to close position, thereby holding thesubstrates1801 at the edges, fully exposing both surfaces of thesubstrates1801.

The top callout inFIG. 18 illustrates an embodiment of an actuator mechanism for a universal carrier that may be used with different sizes and different types of substrates in the same processing system, whether in horizontal or vertical orientation. The universal carrier has a travelingrail1805 at each edge for engaging a transport mechanism. Anactuator1811 is provided on eachrail1805, theactuator1811 is configured for opening and closing theelongated sidebars1802 using a sliding operation, as shown by the arrows. Theactuator1811 also locks thesidebars1802 in place at the desired opening size—depending on the width of the substrate. Each of thesidebars1802 has substrate retaining clips1808. Also, for vertical processing each sidebar may also have support clips (obscured from view by thesubstrates1801 inFIG. 18). Theactuator1811 comprises carrier clamps1804, which are made of magnetic material, such as, e.g.,400 series magnetic stainless steel, so that they can be actuated with electromagnets. Aclamp bar1817 has grooved surface and engages grooved surface on bottom of thecarrier clamp1804 to lock the clamp in a desired place. Springs (hidden from view) push the carrier clamps into contact with the clamp bar. Aslide block1816 has linear bearings for riding on thelinear rails1819 providing slide block motion.

With respect to the embodiment ofFIG. 18, the loading operation is as follows. A horizontal empty carrier moves to the load position. The carrier is always loaded and unloaded in a horizontal orientation, regardless of whether the processing is done in horizontal or vertical orientation. Four electromagnets (not shown—provided on the system's chamber) engage the fourcarrier clamps1804 and are energized, thereby lifting or disengaging theclamps1804 from theclamp bar1817. Electromagnets on four independent linear slides open thecarrier side walls1802. Thesubstrates1801 are lifted between the carrier side rails1802. The substrates are lifted into a carrier where the side walls orsidebars1802 are opened wider than the width of the substrates. Thesidebars1802 are then moved to desired position to retain the substrates by theclips1808 and are then locked firmly in place by theactuator1811. For example, the electromagnets on the four independent linear slides close thecarrier side walls1802 by moving in to a fixed distance, such that the spring clips1808 hold the substrates at their edges. The operator would have chosen the panel size from the user interface. The electromagnets are de-energized, allowing the carrier clamps1804 to engage theclamp bar1817. This firmly holds the carrier side rails at the required distance for the selected panel size. The loaded carrier moves to a buffer area where it can be moved to vertical orientation for processing if vertical processing is desired. Another empty carrier moves to load and the process repeats. The unloading process is essentially the reverse of the above steps.

FIGS. 19A and 19B illustrate an embodiment of asimple substrate clip1908, which can be used in a dual-sided flip carrier for different size and different types ofsubstrates1901. The clip can be manufactured inexpensively from sheet metal. When used for fabrication of thin substrates, such as, e.g., solar cells, the clips are configured so as not to exert pressure on the substrate. That is, in close position the opening between the clips equals the width of the held substrate.

One feature of the clips is that they are self-shadowing. This feature is particularly important when the fabrication includes deposition of material on the substrate. As seen inFIG. 19B, the clips have an “S-shape” wherein the top of the S curve faces the direction of deposited material. The arrows inFIG. 19B illustrate the deposition material reaching thesubstrate1901, but not the interior part of the S-curve of the clip. Consequently, the interior of the clip does not accumulate deposition material, such that it prevents deposition material particles from falling on subsequent substrates.

FIGS. 20A and 20B illustrate an embodiment of automation arrangement for loading and unloading substrates from carriers. The load/unloadmodule2000 has anincoming substrate conveyor2005,outgoing substrate conveyor2010, substrateload robot blade2007, substrate unloadrobot blade2017,incoming substrate lift2020 andoutgoing substrate lift2027, substrate load/unloadstation2030,optional carrier actuator2032, carrier lift pins3034,carrier return lift2040, which may be configured as the lift illustrated inFIG. 16, twocarrier buffers2050 and2052, with optional tilt mechanism if required for vertical processing. Each of the carrier buffers are positioned inside a carrier load lock (not shown) and is situated on the other side of the elevator than the loading station. That is, the elevator is positioned such that the load station is on one side and the buffer station is on the opposite side of the elevator.

As a carrier enters the unloadingstation2030, the substrate unloadrobot blade2017 lifts the substrates from the carrier. The carrier then moves to the loading station, while the unloadingrobot blade2017 lowers the substrates ontooutgoing substrate conveyor2010. Meanwhile,incoming robot blade2007 removes fresh substrates fromincoming substrate conveyor2005 and loads them onto the now-empty carrier. The loaded carrier then moves into the lift to be sent back to the system for processing.

FIG. 21 illustrates another embodiment of a loading and unloading module that can be used with various systems as disclosed herein. This simplified load/unload station uses no robots and no robot blades. Also, the design of this station enables loading and unloading substrates without touching the front surface or the sides of the substrates. Only the rear surface is contacted at a few points. The embodiment ofFIG. 21 is illustrated with the adjustable carrier ofFIG. 18; however, the mechanism that opens and closes the sliding rails is obscured. By using the carrier ofFIG. 18, different sizes of substrates can be processed by simple software change and no hardware change. That is, all that is required is to change the software to indicate a different opening and closing width of the sliding rails to accommodate different size substrates. The entire system remains the same.

The load/unloadstation2100 includesincoming substrate conveyor2105,outgoing substrate conveyor2110,incoming substrate lift2120 positioned under theincoming substrates conveyor2105, andoutgoing substrate lift2127 positioned under theoutgoing substrates conveyor2110. Acarrier actuator2132 lowers carriers from upper position to lower position. The substrate carriers moves in the direction illustrated by the unfilled arrows, while the conveyors/substrates move in the direction indicated by the filled arrows.

The exchange of substrates is done according to the following process, wherein the enumerated steps are indicated inFIG. 21 by circled numerals. In step1 theincoming substrates2111 are delivered by advancing theincoming substrate conveyor2105 one pitch. One pitch equals the cumulative length of all of the substrates positioned on one carrier. Instep2, acarrier2101 with processed substrates is returning from the processing system. Instep3 thecarrier2101 is positioned at the carrier unloadstation2131. At this position the unload substrates lift2127 is raised to engage the processed substrates, the slidingrails2102 of the carrier are extended to the open position so as to release the substrates to the unload substrates lift2127, and the unload substrates lift2127 is lowered so as to deposit the processed substrates onto theoutgoing substrate conveyor2110. Atstep4 the carrier is then moved to theload station2133, the sliding rails still being in the open position. In this position theload carrier lift2120 lifts fresh substrates to position the substrates such that the sliding rails can be closed to engage the substrates with clips. If vertical processing is used, the substrates are positioned such that the bottom edge lines up just above bottom edge support for vertical operation. Once the sliding rails close and engage the substrates with the clips, theload carrier lift2120 can be lowered. The carrier is then moved tocarrier elevator2132 instep5, and the elevator moves the carrier with the fresh incoming substrates to the lower row. The carrier is then moved in step6 into a load lock (not shown) or onto a tilt buffer for vertical operation. Meanwhile, as indicated bystep7, theoutgoing substrates conveyor2110 is activated to move one pitch, so as to remove the processed substrates from the system.

The sequence of operation of the automation arrangement for loading and unloading substrates from carriers in an embodiment ofFIG. 21 can be summarized as follows. After the last processing step and exiting vacuum, the upper row of carriers shift one step left. The load conveyor belt shifts substrates into load position, while the unload conveyor belt shifts substrates away from the unload station (after having processed substrates deposited thereupon). The sliding rails of the loaded and the empty carriers are opened, such that the loaded carrier releases the processed substrates to the unload lifters, while the substrate lifters at the load conveyor raise fresh substrates into position until the substrates are clipped into the carrier. Meanwhile, the carrier elevator drops to lower row position to lower an already loaded carrier. At this stage the substrate lifters position the bottom edge of the substrates per operator designated substrate width. This is done by selecting positions using a user interface to the system's controller. As the unload carrier opens so that the unload lifters can remove the processed substrates, the load carrier closes to capture the fresh substrates, and the lower row of carries shift one position to the right, i.e., towards the system. The load carrier closes per operator designated substrate width. Then, the substrate lifters lower and the carrier elevator rise in preparation for the next loaded carrier. The sequence then repeats.

FIG. 22 illustrates an embodiment of substrate carrier arrangement that can be processed in a horizontal or vertical orientation, whileFIG. 23 illustrates the arrangement ofFIG. 22 in a vertical placement. Specifically, thecommon rails2205 incorporate abar2209 made of paramagnetic material. The system is equipped with row ofmagnetized rollers2267 on each side of processing chambers, such that the carriers are magnetically attached to the rollers. This provides at least two benefits. First, when the rollers are rotated, there's no slippage between the roller rotation and motion of the carrier, so that carrier motion can be tightly controlled. Second, as illustrated inFIG. 23, for vertical processing the rollers are provided on top and bottom of the processing chamber, and the carriers are still magnetically attached to the rollers, but in vertical orientation. In vertical orientation, abottom roller2269 is added to support and guide the bottom rail of the carrier. Also, ashield2224 is provided so as to prevent any particles generated from the roller mechanism contaminating the substrates. Theshield2224 includes anextension2226 that is configured to be housed inside acorresponding cavity2228 that is provided in the common rails. Theextension2226 basically wraps around thebar2209, such that thebar2209 is situated between theroller2267 and theextension2226.

The carrier ofFIGS. 22 and 23 comprises basically of twocommon rails2205 and aplanar panel2207 attached to the rails. Theplanar panel2207 includes clips, such as those illustrated in the callout, so as to hold the substrates in place. Thepanel2207 may be solid panel, in which case the clips may simply urge the substrates against the solid panel. Conversely, thepanel2207 may have cutouts formed like the interior of a picture frame, wherein the substrates are urged against a lip of the cutout, just like a picture glass is urged against the frame.

FIG. 24 illustrates an embodiment of substrate carrier arrangement that can be flipped so as to process both surfaces of the substrates. As illustrated inFIG. 24, eachcommon rail2405 has twobars2409 made of magnetic material—one on top and one on bottom of the common rail. Thebody2407 of the carrier has clear cut outs, each cut out sized to be larger than the substrate, such that a space exists between the periphery of the substrate and the edge of the cut out. This can be seen more clearly in the dashed-dot callout ofFIG. 24.Clips2408 hold the substrate within the cut out. In this manner, both front and back surfaces of the substrate are exposed. The carrier is fabricated to be symmetrical and hold the substrates in the center, such that in effect there is no front and back, but simply two sides, wherein either side provides equal access to the surface of the substrate.

FIG. 25 illustrates an embodiment of a system wherein the substrate carrier arrangement can be flipped so as to process both surfaces of the substrates. The carrier illustrated inFIG. 24 can be advantageously used in this system. This embodiment illustrates a system wherein the carriers are flipped in vacuum; however, if desired, the same arrangement can be used to flip the carriers in atmosphere. Flipping the carrier in vacuum is preferred when successive processes steps should be performed without breaking vacuum in between. In the particular example ofFIG. 25 two flipping stations are illustrated as an example, but fewer or more flipping stations may be used. In the system ofFIG. 25, the carrier with the substrates traverses afirst processing chamber2501 and asecond processing chamber2502. For example, in chamber2502 a metal layer may be deposited on one surface of the substrate.

The carrier then moves into the first flippingstation2511. In the flipping station the carrier moves into a rotatable cradle2520. Cradle2520 has magnetizedwheel arrangement2567, such that the carrier is held in place. The cradle is then rotated aboutaxis2530. Again, since the carriers are magnetically held by themagnetized rollers2567, the cradle2520 assembly with thecarrier2530 can be rotated and the carrier would be help upside-down by the magnetic force of the rollers. Thecarrier2530 then moves to the next station within the flipping station, wherein the rollers are below the carrier, so that the carrier now presents the other surface of the substrates. The substrates remain clipped to the carrier throughout this process.

Once flipped, the carrier moves into thenext processing station2503. For example, a metal layer can now be deposited on the other surface of the substrates. In this particular example, the carrier then moves to yet anotherprocessing chamber2504. This may be, for example, a second metal layer over the first metal layer. The carrier may then move to another flipping station or, if processing is completed, the second flipping station may be omitted and the carrier moved to a load/unload station.

While this invention has been discussed in terms of exemplary embodiments of specific materials, and specific steps, it should be understood by those skilled in the art that variations of these specific examples may be made and/or used and that such structures and methods will follow from the understanding imparted by the practices described and illustrated as well as the discussions of operations as to facilitate modifications that may be made without departing from the scope of the invention defined by the appended claims.

Claims (21)

The invention claimed is:

1. A system for processing substrates in vacuum processing chambers, comprising:

a plurality of carriers, each carrier configured for supporting and transporting substrates throughout the system and inside the vacuum processing chambers;

each of the carriers comprising clips for holding substrates while exposing both surfaces of each substrate;

each of the carriers comprising two paramagnetic common rails at each end thereof;

a plurality of magnetized rollers for transporting the carriers throughout the system, by engaging and magnetically holding the common rails;

a flip station comprising a rotatable frame coupled to a rotating axis, and wherein a subset of the plurality of magnetized rollers is positioned on each end of the frame; and,

wherein each of the carries further comprises two sliding rails configured for holding different substrates of different sizes.

2. The system ofclaim 1, wherein each of the carries is configured for supporting a linear array of 1×n substrates, wherein n is an integer larger than 1.

3. The system ofclaim 1, wherein the sliding rails are spring-loaded in close position.

4. The system ofclaim 1, wherein the carriers are transported inside the vacuum processing chambers in a vertical orientation thereby carrying the substrates in a vertical orientation.

5. The system ofclaim 1, further comprising a conveyor for returning carriers to the loading station after completion of processing.

6. The system ofclaim 5, wherein the conveyor passes above the vacuum processing chambers in atmospheric environment.

7. The system ofclaim 1, further comprising a carrier elevator coupled a loading/unloading station.

8. The system ofclaim 7, wherein the carrier elevator comprises a plurality of vertically oriented conveyor belts, each conveyor belt having a plurality of pins extended to engage the common rails.

9. The system ofclaim 7, wherein the loading/unloading station comprises an incoming substrate conveyor, an outgoing substrate conveyor, a substrate load lifter, substrate unload lifter, and carrier actuator configured for actuating the carrier to release its substrates.

10. The system ofclaim 9, further comprising mask loading mechanism for loading masks onto the carriers.

11. The system ofclaim 9, wherein the loading/unloading station comprises an upper carrier transport and a lower carrier transport spaced vertically below the upper carrier transport, and wherein the incoming substrate conveyor and the outgoing substrate conveyor pass in a space positioned vertically between the upper carrier transport and the lower carrier transport.

12. The system ofclaim 7, wherein the loading/unloading station further comprises retractable substrate alignment pins configured to align substrates loaded onto the carriers.

13. A system for processing substrates in vacuum processing chambers, comprising:

a plurality of carriers, each carrier configured for supporting and transporting substrates throughout the system and inside the vacuum processing chambers;

each of the carriers comprising clips for holding substrates while exposing both surfaces of each substrate;

each of the carriers comprising two paramagnetic common rails at each end thereof;

a plurality of magnetized rollers for transporting the carriers throughout the system, by engaging and magnetically holding the common rails;

a flip station comprising a rotatable frame coupled to a rotating axis, and wherein a subset of the plurality of magnetized rollers is positioned on each end of the frame; and,

wherein each of the plurality of magnetized rollers comprises a rotating shaft having a plurality of magnetic wheels attached thereto in alternating magnetic polarity.

14. The system ofclaim 13, wherein each of the shafts it rotated by a flexible tension element.

15. The system ofclaim 14, wherein the flexible tension element comprises a belt or a chain.

16. A universal carrier that may be used with different sizes and different types of substrates, comprising:

two traveling rails, one at each edge for engaging a transport mechanism;

two elongated sidebars, each connected to the traveling rails at the edge thereof;

a plurality of retaining clips provided on the sidebars and configured for engaging an edge of a substrate for holding the substrate without touching any surface of the substrate;

two actuators provided on each traveling rail, each actuator configured for opening and closing a corresponding sidebar using a sliding operation;

a locking mechanism provided on the actuator to lock the corresponding sidebar in a desired slide position; and,

wherein the actuator comprises carrier clamps made of magnetic material.

17. The universal carrier ofclaim 16, further comprising a plurality of support clips provided on the sidebars.

18. The universal carrier ofclaim 16, wherein the actuator further comprises clamp bar that has grooved surface and engages grooved surface on bottom of the carrier clamp to lock the clamp in a desired place.

19. The universal carrier ofclaim 18, wherein the actuator further comprises springs configured to push the carrier clamps into contact with the clamp bar.

20. The universal carrier ofclaim 19, wherein the actuator comprises a slide block having linear bearings for riding on linear rails.

21. The universal carrier ofclaim 16, wherein the actuator comprises a slide block having linear bearings for riding on linear rails.

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